1. Field of Invention
The present invention relates to protective inserts for electrical utility meter sockets.
2 Description of Prior Art
In electrical power distribution, it has been common practice for service crew members to take electrical measurements or readings from terminals in electrical meter boxes. Voltage readings or phase rotation indications are examples of these types of measurements. There has been a possibility of injury, since the crew member was working with energized terminals. An inadvertent short circuit could possibly be formed between two energized terminals, or an energized terminal could be mistakenly shorted to ground.
There have been several types of meter testing jacks in the prior art. Examples are U.S. Pat. Nos. 2,218,650; 2,225,122 and 1,028,254. These have been generally relatively simple, panel or board-like items with a set of blades on one side for insertion into the jaws within the meter box. A corresponding set of spring contacts or jaws for test connections was provided on an opposite side of the panel in electrical contact with the insertion blades. One problem with this type of structure was that test connections were difficult to make with the spring contacts, since the contacts were designed to receive and connect with the meter blades. Also, in testing electrical power lines at meter boxes, one set of terminals, termed the line side, was electrically energized. The other set of terminals, known as the load side, could have an inadvertent short between terminals. There was thus a need for some capability to separate testing connections between the line side and the load side.
Other prior art patents provided inserts, also termed adapters or extenders, which were adapted to be connected by blades on one side inserted into the meter box jaws. These types of inserts were used for testing of various functions, such as watt hour meter testing or testing for energy diversion, or for connection of tamper proofing structures. Patents in this category included U.S. Pat. Nos. 4,583,043; 4,404,521; 4,121,147; 4,271,390; and 2,249,075.